Wood grinding machine



Feb. 20, 1934. RUSSELL 5 AL 1,948,189

WOOD GRINDING MACHINE Filed Feb. 27, 1930 3 Sheets-Sheet 1 INVENTORSANDREWJLRIISSELL L a 1-D. ROBB A'IIORNEI S Feb. 20, 1934. A, RUSSELL ETAL 1,948,189

WOOD GRINDING MACHINE Filed Feb. 27, 1930 3 Sheets-Sheet 2 INVENTOBSANDREWMJIUSSEU J. D-ROBB ATTORNEYS Feb. 20, 1934. N RUSSELL r AL1,948,189

WOOD GRINDING MACHINE Filed Feb. 27, 1930 3 Sheets-Sheet 3 a g g (LI :1

TNV ENTORS A'NDREWJl-RUSSELL J- D- RD BB BY vwwz/ lrz;

ATTOPLNEY$ Patented Feb. 20, 1934 UNITED STATES PATENT OFFICE WOODGRINDING MIACHINE Andrew N. Russell and John D. Robb, Lachine,

8 Claims.

v This invention relates to pulp wood grinders of the continuous feed ormagazine type.

The pocket type of grinder in general use before the advent of themagazine grinder consisted of a plurality of wood receiving pocketsequipped with hydraulic pressure plates or followers functioning to feedthe wood to the working surface of the grinding element. This type ofgrinder has certain advantages incident to the 10 direct application ofhydraulic or elastic operating fluid, but the disadvantages, such ashigh operating cost with comparatively low output, led to thedevelopment of the magazine grinder.

Magazine grinders are usually equipped with endless belts havingspecially formed links or other devices for engaging and. feeding thewood to the working surface of the grinding element. These chains areoperated at a very slow constant speed from either an oil or an electricmotor through the intermediary of a complicated reduction gearing. Thisarrangement, as compared with the pocket type grinder, provides forcontinuous feeding of the wood to the grinding element and has certainother advantages, such as low labor costs incident to magazine chargingand general operation. The principal disadvantage of the magazinegrinder resides in the fact that the chains or other devices employedfor feeding the wood to the grinding element are operated by a drivingmechanism which lacks the elasticity of the direct hydraulic feedemployed in the pocket type grinder and it is well recognized that, froma grinding standpoint, the best results are obtained when the wood ispressed to the grinding surface by the direct application of fluidpressure.

The purpose of the present invention is to provide an improved type ofmagazine grinder in which the wood is continuously fed to the work- 40ing surface of the grinding element by the direct application of fluidpressure.

According to this invention, the wood charge placed in the magazine iscontinuously fed to the working surface of a rotary grindstone by meansof two groups of reciprocable feed members arranged at opposite sides ofthe magazine and actuated by the direct application of fluid pressure..These feed members are each provided with a plurality of pivotallymounted pawls normally arranged to apply feeding pressure to the woodcharge only during movement of the members in the direction of thegrindstone. During reverse movement of said members, the pressureapplying pawls are automatically retracted from engagement with the woodcharge so that the feeding members are permitted to slide freely pastthe wood during such return movement. Each feed member is connected to apiston operating in a cylinder equipped with a valve controlling theflow of operating fluid in such 0 manner that the piston and the feedmember connected therewith are alternately moved towards and awayfrom'the grindstone. Thev application of a relatively high pressure tomove the feed members on their working strokes and a U5 relatively lowpressure to effect return movement of the'feed members is described andclaimed in applicants co-pending application Serial Number 612,125,filed May 18, 1932. The valves controlling the various cylinders may beoperated either I0 manually or automatically in order to reverse themovement of the pistons and the feed members connected therewith, but itis preferred that these valves be operated in such a manner that whenone of the feed members is moving away '15 from the grindstone, theremaining feed members will all be moving in the opposite direction, sothat the mass of wood contained in the magazine will be continuouslysubjected to a substantial and uniform feeding pressure. For example,assuming that four feeding members are provided at each side of themagazine, the flow of fluid to and from the cylinders controlling saidfeed members will preferably be controlled in such manner that when oneof the feed members is 86 moving away from the grindstone the remainingfeed members will be moving in the direction of said stone, so that thecharge of wood is, at all times, subjected to the pressure of seven ofthe operating cylinders. As the rate at which the 90 feed members move,during the working strokes, is retarded by the grinding operation and isconsiderably slower than the rate at'which the feed members move duringthe return strokes, it will be seen that the period of time when onlyseven of the eight cylinders are applying pressure to the wood will becomparatively short and that, during the greater part of the grindingoperation, the Wood is subjected to the pressure of all of saidcylinders. When it is desired to remove the load fromthe grindstone, thefeeding members may be employed as lifting devices for lifting the woodcharge away from the working surface of the stone. In order toaccomplish this, suitable means are provided for securing the pawls ofcertain feed members against pivotal'movement so that, during the returnstroke of said members the pawls will apply pressure to move the woodcharge in a direction away from the working surface of the stone.

Proceeding now to a more detailed description of this invention,reference will be had to the accompanying drawings, in which Figure 1 isa view partly in side elevation and partly in vertical section of a pulpwood grinder constructed in accordance with this invention.

Figure 2 is a view similar to Figure 1, but taken at right anglesthereto.

Figure 3 is a fragmentary transverse sectional View through a part ofthe magazine taken substantially along the line 33 of Figure 1.

Figure 4 is a diagrammatical view of an electric control means fortiming the return or nonworking strokes of the feed members.

Figure 5 is a detailed view of a locking device employed for tying downthe pawls of the feed members when these members are to be employed forlifting purposes.

Figure 6 is an enlarged detailed view showing the manner in which thecylinders controlling the feed members are mounted in the magazine.

Figure '7 is a diagrammatic view of a hydraulic machine controlling theoperation of the feed members.

Figures 8 and 9 are views of details embodied in the construction shownin Figure 7.

Referring more particularly to the drawings, 11 designates a rotarygrindstone carried by a shaft 12 journalled in suitable bearings 13.These bearings 13, together with spaced side frames 14 and 15, aremounted upon a suitable base plate 16. The upper ends of the side frames14 and 15 are connected by cross members 1'7.

v Mounted on each cross member 17 are a plurality of casings 18 carryingvertically movable screws 19 adapted to be operated by any suitable formof gearing such as the worm gearing generally indicated at 20. The lowerends of the screws 19 are fii'red to a supporting frame or casing'21forming the lower end of a magazine 22. The frame or casing 21 is ofwell-known construction and is adapted to have its lower face maintainedin proper relation to the working surface of the grinding element 11' bysuitable adjustment of the screws 19.

The magazine structure includes a series of flanged beams 23 arranged atopposite sides of the magazine and spaced apart, as shown in Figure 3,to provide a plurality of vertical guide ways 24. Mounted in each guideway 24 is a reciprocable feed member comprising a pair of side plates 25having their upper and lower extremities joined together by suitablecross members 26. Each feed member carries a plurality of verticallyspaced pawls 27 mounted between the side plates 25 on suitable pivotpins 28. The pawls 27 are normally balanced on the pivots 28 so that theheel portions 29 rest on cross bars 30 connecting the side plates 25,while the toe portions 31 project beyond the side plates 25 and into thewood receiving space of the magazine. Each feed member is connected to apiston rod 32 by a pin 33 passing through the lower end of said rod andthrough suitable lugs 34 carried by the upper cross member 26. The upperend of each piston rod 32 is connected to a piston, not shown, operatingin a cylinder 35. Each cylinder is equipped with a valve casing 36containing a reciprocable fluid control valve having a stem 37connectedto the armature 38 of a solenoid 39. The side plates 25 carry rollers25a arranged to travel along the outer flanges of the beams 23.

From the foregoing, it will be understood that the feed membersoperating in the vertical guide ways 24 are raised and lowered as theoperating Waist is such that pressure is applied to the wood charge in adirection at an angle of about 45 with respect to the direction ofmovement of the feed members, with the result that the applied pressureis distributed throughout the entire mass of the wood charge. During theupward movement of the feed members, the pawls 27 swing about the pivotpins 28 so that the toe portions 31 are retracted from engagement withthe wood charge 40, with the result that substantially no resistance isoffered to the upward movement of the feed members.

In the present instance, we have shown the feed members arranged in twogroups (of four each) located at opposite sides of the magazine and itis desired that the movement of these feed members be controlled, sothat, when one feed member is moving upwardly, the remaining feedmembers will be moving downwardly, where= by the wood charge is at alltimes subjected to the pressure of at least seven of the cylinders 35.To accomplish this we may, as diagrammatically shown in Figure 4, employa very simple form of electrical control including a stationary disc 41arranged to surround a shaft 42 which equipped with a pulley 43 drivenby a belt 44 from a pulley 45 fixed to the shaft 12 of the grindstone11. The disc 41 carries, in the present instance, eight stationarycontact points 46 and each contact point is electrically connected asdiagrammatically indicated at 47, to a ter minal of one of the solenoids39, the remaining terminal of each solenoid being connected by a lead39a to a suitable source of current supply, (not shown). The shaft 42carries a movable contact engageable with each of the stationary contactpoints 46. The said movable contact 48 may be connected by a wire 48a tothe aforesaid source of current supply.

The movable contact 48 revolves at a speed proportionate to the numberof strokes per minute of the hydraulic pistons and as this contactengages each of the stationary contact points '46, the valve operatingsolenoid controlled by said stationary contact point is energized tocause fluid to be admitted to the lower end of one of the cylinders 35,whereby the feed member controlled by said cylinder is moved upwardly ina direction away from the grindstone. As the movable contact 48disengages said stationary colitact point 46, the position of the valveassociated with said cylinder 35 is reversed by it's own Weight so thatfluid is then admitted to the upper end of the cylinder for moving thefeed members downwardly upon the working or pressure applying stroke, inthe course of which the pawls 27 engage and apply pressure to the woodcharge, as previously explained. With this form of electrical control,it will be seen that the feed members are automatically moved upwardlyon the return stroke at predetermined intervals "or time, regardess ofwhether or not the said feed members have completed or only partiallycomvantage of this arrangement resides in the fact that when one of thefeed members becomes jammed during the working stroke, it will remaininactive only during the interval of time required for the solenoidcontrolling the same to be energized by engagement of the movablecontact 48 with the proper stationary contact 46. As soon as thisengagement of contacts occurs, the feed member is quickly raised to theend of its return or non-working stroke and then begins immediately tomove downwardly on the working stroke.

It will also be evident that as the feed members move freely past thewood charge during the return or non-working strokes, these members willnot become jammed by the arching or bridging of the wood within themagazine. When such arching or bridging of the wood does occur, thepressure applying strokes of the feed members will, of course, beretarded, but, at predetermined intervals, controlled by the movablecontact 48 and the stationary contact 46, each feed member will movefreely on its return stroke and will then immediately move in a reversedirection to apply pressure to the wood charge at a somewhat differentpoint. In other words, whenever there is arching or bridging of the woodwithin the magazine, the limited reciprocating movement which the feedmembers are permitted to have results in the pawls 27 constantlychanging their positions to apply pressure to different portions of thewood charge until the arch or bridge is broken down.

While the electrical valve controlling mechanism described in theforegoing operates satisfactorily we prefer, for economical and otherreasons, to employ the hydraulic valve controlling mechanism shown inFigures 7 to 9 inclusive. In these figures we have shown feed members 57and 58 connected, respectively, to pistons 59 and 60 operating in powercylinders 61 and 62. Each power cylinder is equipped with a valve casing63 housing a slide valve 64. The upper and lower ends of each valvecasing are connected by branches 65 to an exhaust 66, while theintermediate portion of said valve casing is connected to a highpressure oil line 67. The valves 64 are connected, respectively, byvalve stems 68 and 69 to auxiliary pistons 70 and 71 operating in theauxiliary cylinders 72 and 73. The upper end of cylinder 72 is connectedto one end of a pipe 74, the other end of which is provided withbranches 75 and 76. The branch '75 communicates with a compartment 76aformed in the upper portion of a pilot valve casing 77. This compartment76a is separated from a lower compartment 78 by a valve 79 which is heldto its seat by a spring 80 surrounding the valve stem 81 between theupper end of the valve casing 77 and a suitable abutment 81a. The branch76 of pipe 74 communicates with a compartment 82 formed in the lowerportion of a second pilot valve casing 83 and is separated from an uppercompartment 84 by means of a valve 85, which is held to its seat by aspring 86 arranged substantially as described in connection with spring80 of the valve 79. The lower compartment 78 of valve casing 77 isconnected to a fluid pressure supply line 87, while the uppercompartment 84 of the valve casing 83 is connected to an exhaust line88. The valve 79, which controls communication between the compartments76a and 78 of valve casing 77, is normally held closed by the spring 80but is adapted to be periodically opened through the instrumentality ofa rotary cam 89 mounted on a shaft 90. Cam 89 is provided with aprojection 91 functioning, periodically, to depress a lever 820. havingone end bearing'on the upper end of the valve stem 81. The valve isnormally held in ppen position by a pivoted lever 91a bearing on thestem of valve 85 and provided with a projection 92 which is presseddownwardly by engagement with a cam 93. This cam 93 is provided with anotch 94 adapted, when posiadapted at times to be caught beneath thecurved prongs 102 of a catch member 103. This catch member is verticallyadjustable along the length of a suitable guide 104 and may be securedin adjusted position by any suitable means, such as the set screwindicated at 105. This engagement of the bar 101 beneath the prongs 102limits the movement of the attached cable in the direction of the pullexerted by the counter weight 100. Each of the feed members 57 and 58 isequipped with a pair of curved prongs 106, adapted, during downwardmovement of the feed member to pass between the prongs 102 and byengagement with the cross bar 101 exert a downward pull on the cableattached to said cross bar. When these feed members 57 and 58 reach theends of their upward strokes, the prongs 106 carried thereby are spacedabove the prongs 102 of the co-operating catch member 103. By reason ofthis arrangement, it will be evident that, for reasons to be hereinafterexplained, each feed member is permitted to move downwardly a limiteddis tance before exerting a downward pull on the co-operating cable.

The auxiliary cylinder 73 is connected by a pipe 107 to pilot valvecasings 108 and 109 corresponding, respectively, to the casings 77 and83 described in connection with the auxiliary cylinder 72. These casings108 and 109 are provided with valves -110 and 111 corresponding,respectively, to the valves 79 and 85 and controlled by cams 112 and 113corresponding, respectively, to the cams 89 and 93. The pilot valvecasings 108 and 109 are also respectively connected to the pressure andexhaust lines 87 and 88 in the same manner as described in connectionwith the pilot valve casing 83.

In the operation of the hydraulc valve control mechanism described inthe foregoing, it will be understood that, while only two power pistons59 and 60 having been actually shown, any number of these pistons may beemployed and the same will preferably be arranged as explained inconnection with Figures 1 to 6 inclusive. During the downward movementof these power pistons, rotation is imparted to the cam shaft throughthe medium of the pulley and cable connection provided between eachpiston and the cam shaft. As the descending speed of the various powerpistons will vary according to the resistance offered by the woodcharge, it will be understood that the cam shaft 90 will be driven, at agiven time, by the power piston which happens, at that particular time,to be moving downwardly at the greatest rate of speed. At such a time,the driving pawls 97 of all the pistons. "ders are firing at a fixedtime interval and in regular succession.

pulleys on shaft 90 except the pulley'which happens to be functioning asthe driving pulley, will slip freely on the engaging ratchet wheels 98.

At certain intervals, during rotation of cam shaft 90, the pilot valve79 will be opened by the cam 89 while, at the sametime, theco-operati'ng pilot valve 85 will be permitted to close under the actionof the spring 86 by the movement of the cam 93 to position the notch 94in line with the projection 92; The closing of pilot valve 84 disruptscommunication between the pipe 74 and the exhaust line 88, while theopening of the pilot valve 79 places said pipe 74 in communication withthe pressure line 87. Fluid under pressure is thus permitted to flowinto the upper end of the auxiliary cylinder 72 to cause downwardmovement of the auxiliary piston 70. This downward movement of auxiliarypiston causes a corresponding downward movement of the attached slidevalve 64, so that the lower end of power cylinder 61 is placed, by meansof the port 61a, in communication with the high {pressure oil line 67,while, at the same time the the-action of the spring 80, while the valveis'again moved to open position against the resistance of the spring 86.This closure of valve 79 disrupts communication between the pipe 74 andthe pressure line 87, while the opening of valve 85 places said pipe 74in communication with the exhaust line 88. This permits the auxiliarypiston 70 to be moved upwardly or reset by a suitable arrangement ofsprings 118 associated therewith as shown to advantage in Figure 8.

Each piston operates in the same manner as described in connection withpiston 59, but the 'set of cams controlling the pilot valves co-op-"erating with the slide valve of each power cylinder will have a certainangular displacement about the cam shaft with respect to "the sets ofcams controlling the operation of the pilot valves co-operating with theremaining power "cylinders. In this way, the operation of the slide'valve associated with each power cylinder is "timed so that the pistonoperating in said cylinder will begin its upward or non-working strokeat a different time compared with the beginning of the upward stroke ofeach of the remaining Hence, it may be said that the cylin- The powerpiston connected to each of the feed members may have a tendency to droprapidly at the beginning of the downward or power stroke, due to thefact that during the first few inches of this stroke, the pawls carriedby the feed members may not be brought into pressure applying engagementwith the wood charge.

It is desirable to prevent the rapid revolution of the cam shaft 90 inresponse to this quick initial drop of the feed members and powerpistons associated therewith and this is accomplished through theinstrumentality of the co-op- 'erating prongs 102 and 106, previouslyreferred to.

It may also be advisable to provide manual control means for permittingthe power pistons to be reversed by hand at any time either individuallyor in series. To this end, a lever 120 is pivoted to the stem of eachmain valve 64. The inner end of this lever is fulcrumed against thelower end of the adjacent power cylinder, while the outer end of saidlever is attached to an operating cable 121.

In connection with both the electric and hydraulic valve operatingmechanisms herein disclosed, it will be noted that the feed members arecontrolled so that when one feed member is moving on the return ornon-working stroke, all the remaining members will be moving in thereverse or pressure applying direction so that'the wood charge will becontinuously subjected to an adequate and substantially uniformpressure.

In this connection, it may be pointed out that the feed members completethe return or nonworking stroke in a relatively short period of time,as, during this stroke, the pawls 27 assume positions permitting thefeed members to move freely past the wood charge. ,A much greater time,however, is obviously required for completing the working or pressureapplying stroke of each feed member, due to the fact that,

during the working stroke, the rate at which the feed members move isdependent upon the rapidity of the grinding action. Hence, as the returnstroke of each feed member is completed within a shorter time, than theworking stroke, it will be evident that during the greater portion ofthe grinding operation the wood. charge is subjected to the pressure ofall of the operating cylinders.

When it is desired to remove all load from the grindstone 11, certain ofthe feed members may be employed as lifting devices for moving the woodcharge away from the working surface of the stone. To this end, the heelportions of the pawls 27 carried by two opposing feed, members aresecured to the cross bars 30 by means of clamps 50 held in place bysuitable screws 51. The pawls are thus tied down to maintain ahorizontal position during upward movement of the feed members so thatthe wood charge is raised with reference to the working siu-face of thegrindstone. The feed members to be employed as lifting devices as hereindescribed, are preferably operated manually by the valve controllinglevers indicated at 120 in Figure 7.

In order to facilitate the positioning and removal of the cylinders 35with reference to the guide ways 24, it will be noted that flangeportions of the beams 23 are removed, as indicated at 52, to provideopenings large enough to permit the cylinders to be passed laterallytherethrough during insertion and removal. Cylinder supporting blocks 53are fastened to the beams 23 at opposite sides of these openings and thecylinders 35 are formed with upper and lower shoulders 54 and 55 adaptedto engage the upper and lower ends of the said blocks, as shown tadvantage in Figures 2 and 6.

After the cylinders 35 are mounted on the blocks 53, they may beretained in place by suitable cover plates 56 fastened to the beams 23in a suitable manner and provided with openings permitting the valvecastings 36 to project therethrough.

Having thus described our invention, what we.

claim is:-

l. A pulp wood grinder equipped with reciprocable feed members havingpawls arranged to apply feeding pressure to the wood charge during theworking strokes of said. members and to slip 1150 freely past the woodcharge during the return strokes of said members and locking meansadapted to be applied to the pawls of certain of said members so as toretain said pawls in lifting engagement with the wood charge during thereturn stroke of said members.

2. A magazine pulp wood grinder of the continuous feed type comprising amagazine structure having opposing series of guideways arranged atopposite sides of the magazine, a reciprocable feed member in eachguideway comprising a pair of side plates, a plurality of verticallyspaced pawls pivotally mounted between the side plates on pivots passingthrough intermediate portions of the pawls and cross bars connecting theside plates, said pawls being normally balanced on the pivots so thatthe heel portions rest on the cross bars while the toe portions projectbeyond the side plates and into the wood receiving space of themagazine.

3. A magazine pulp wood grinder of the continuous feed type comprising amagazine structure having opposed series of vertical guideways arrangedat opposite sides of the magazine, a reciprocable feed member in eachguideway comprising a pair of side plates, a plurality of verticallyspaced pawls pivotally mounted between their ends on pivots extendingbetween and carried by the side plates, and cross bars connecting theside plates, said pawls being normally balanced on the pivots so thatthe heel portions rest on the cross bars while the toe portions projectbeyond the side plates into the wood receiving space of the magazine, apiston rod connected to each feed member at the upper ends of the sideplates, a piston connected to each piston rod, a cylinder housing eachpiston, a valve mechanism for controlling the flow of fluid to and fromthe opposite end of each cylinder, and means for timing the operation ofsaid valve mechanism, said means being connected with and actuated bysaid feed members.

4. A magazine pulp wood grinder of the continuous feed type comprisingreciprocable feed members normally functioning to apply feeding pressureto the wood charge only during the working strokes of said members, aseparate pressure responsive operating device for each feed membercomprising a cylinder and a piston operating in the cylinder andconnected to the feed member, a valve mechanism associated with eachcylinder to control the flow of motive fluid to and from opposite endsof the cylinder, a timing shaft, means actuated by said shaft forcontrolling the functioning of all of the valve mechanisms associatedwith the different cylinders so that the feed members are operated in adefinite sequence and means whereby the timing shaft is operated by thefeed members during the working strokes of said members.

5. A magazine pulp wood grinder of the continuous feed type comprisingreciprocable feed members normally functioning to apply pressure to theWood charge only during the working strokes of said members, a pressureresponsive operating device for each feed member comprising a cylinderand a piston operating in the cylinder and connected to the feed member,a valve mechanism associated with each cylinder and controlling flow ofmotive fluid to and from opposite ends of the cylinder, an auxiliarypressure responsive device associated with each valve mechanism foroperating the same, a timing shaft, means actuated by the timing shaftfor operating all of the auxiliary pressure responsive devices in apredetermined sequence and means controlled by the movement of the feedmembers for operating the timing shaft during the working strokes ofsaid members.

6. A magazine pulp wood grinder of the continuous feed type comprisingreciprocable feed members functioning to apply feeding pressure to theWood charge only during the working strokes of said members, a pressureresponsive operating device for each feed member comprising a cylinder,and a piston operating in the cylinder and connected to the feed member,a valve mechanism associated with each cylinder and controlling the flowof motive fluid to and from opposite ends of the cylinder, an auxiliaryfluid actuated pressure responsive device controlling the operation ofeach valve mechanism, valves for controlling the flow of fluid to andfrom said auxiliary fluid pressure responsive devices, a timing shaftand means associated therewith for operating said last mentioned valvesin a predetermined sequence and means whereby the timing shaft isactuated by the feed members during the working strokes of said members.

'7. A magazine pulp wood grinder of the continuous feed type comprisingreciprocable feed members normally functioning to apply feed pressure tothe wood charge only during the working strokes of said members, apressure responsive device associated with each feed member forimparting reciprocating movement thereto and means for operating thepressure responsive devices of the different feed members in apredetermined sequence including a timing shaft,

and control valves actuated by the timing shaft 1 for controlling thefunctioning of all of said pressure responsive devices and drivingconnections between the feed members and the timing shaft whereby saidshaft is actuated by the feed members during the working strokes of saidmembers, the driving connection between each feed member and the timingshaft including pawl and ratchet means permitting said shaft to bedriven at any. given instant by the feed member which happens to betravelling at the greatest rate of speed at that particular instant. v

8. A magazine pulp wood grinder of the continuous feed type comprisingopposing series of vertically extending guideways arranged at oppositesides of the magazine, a reciprocable feed member in each guidewaycomprising a pair of side plates, cross bars connecting said sideplates, a plurality of vertically spaced pawls pivotally mounted betweenthe side plates and normally balanced on the pivots so that the heelportions rest on the cross bars while the toe portions project beyondthe side plates into the wood receiv ing space of the magazine, a pistonrod connected to each feed member at the upper ends of the side plates,a piston connected to each piston rod, a cylinder housing each piston, avalve mechanism for controlling the flow of fluid to and from theopposite ends of each cylinder, an auxiliary pressure responsive deviceassociated with each of said valve mechanisms for operating the same,

a timing shaft, means actuated by the timing shaft for operating all ofthe auxiliary pressure responsive devices in a predetermined sequenceand drive connections between the feed members and the timing shaftfunctioning to operate said shaft during the working strokes of saidmembers.

ANDREW N. RUSSELL.

JOHN D. ROBB.

